The present invention relates to a very low cost portable compact scanner. More particularly it is directed to a compact device employing a single scanning carriage incorporating a reading head and a printing head to permit essentially simultaneous reading and writing of an original document and a copy.
Historically, copies of original documents have been produced by a xerographic process wherein the original document to be copied is placed on a transparent platen, either by hand or automatically through the use of a document handler, and the original document illuminated by a relatively high intensity light. Image rays reflected from the illuminated document are focused by a suitable optical system onto a previously charged photoconductor, the image light rays functioning to discharge the photoconductor in accordance with the image content of the original to produce an electrostatic latent image of the original on the photoconductor. The electrostatic latent image so produced is thereafter developed by a suitable developer material commonly referred to as toner, and the developed image transferred to a sheet of copy paper brought forward by a suitable feeder. The transferred image is thereafter fixed to the copy paper by fusing to provide a permanent copy while the photoconductor is cleaned of residual developer preparatory to recharging. More recently, interest has arisen in electronic imaging where, in contrast to the aforedescribed xerographic system, the image of the document original is converted to electrical signals or pixels and these signals, which may be processed, transmitted over long distances, and/or stored, are used to produce one or more copies. In such an electronic imaging system, rather than focusing the light image onto a photoreceptor for purposes of discharging a charged surface prior to xerographic development, the optical system focuses the image rays reflected from the document original onto the image reading array which serves to convert the image rays to electrical signals. These signals are used to create an image by some means such as operating a laser beam to discharge a xerographic photoreceptor, or by operating some direct marking system such as an ink jet, direct thermal or thermal transfer printing system.
It is generally advantageous if the normally separate document reading and copy printing operations could be combined. If some of these reading/writing functions could be combined, system operation and synchronization could be simplified and system cost reduced through the use of fewer parts.
There are systems in the prior art that address the above identified concerns. For example:
U.S. Pat. No. 4,496,984 to Stoffel and U.S. Pat. No. 4,583,126, a division of the above-identified reference, disclose an input/output scanner for simultaneously reading a document and writing a copy. The document and copy sheet are fed in back to back relation to the read/write station. A monolithic full width reading array reads each line in two steps, to improve resolution. The writing array consists of rows of ink jet nozzles, of which the number and disposition is in direct correspondence to the sensors of the read bar.
U.S. Pat. No. 4,424,524 to Daniele discloses a full width read/write LED array for scanning a document in the read mode or exposing the photoreceptor in the write mode. A Selfoc optical fiber lens array is used for focusing the full width LED array on the document or photoreceptor.
A difficulty with these prior art systems is the complexity and cost of separate components such as the complex optics, photoreceptor and developer in a typical xerographic process such as the Daniele system. In other systems such as the Stoffel system, it is necessary for an operator to manually combine a document and copy sheet into a single unit for manual insertion to the machine feed rolls. Such a system also has a significant cost penalty associated with components such as the monolithic full width reading array. It is an object of the present invention, therefore, to provide a new and improved read/write scanner/printer system in which a read head and print head are both substantially smaller and less expensive than a full width array component, and co-mounted on the same single scanning carriage to substantially simultaneously read a stationary document and print a copy on a copy sheet. It is another object of the present invention to provide a document that is read and a copy that is printed in a series of bands across the document and copy, that is, after each band of information is read and printed, the document and copy sheet are indexed relative to the read and write components so that the next band of information can be read and printed.
Most of the reproduction devices and in particular copiers in commercial utilization are intended for permanent or semi-permanent location in an office environment. Indeed some are so large complex and expensive that only sizable office environments can support the copier. There is, however, a great need for a portable copier. There is a particular need for very low cost very compact copiers which enable convenient reproduction of documents at sites remote from an office environment. While many efforts have been made there is a continuing need for a smaller, more compact, lower cost copying capability.